Submitted as: model description paper 26 May 2021

Submitted as: model description paper | 26 May 2021

Review status: this preprint is currently under review for the journal GMD.

Bedymo: a combined quasi-geostrophic and primitive equation model in sigma coordinates

Clemens Spensberger, Trond Thorsteinsson, and Thomas Spengler Clemens Spensberger et al.
  • Geophysical Institute and Bjerknes Centre for Climate Research, University of Bergen, Bergen, Norway

Abstract. This paper introduces the idealised atmospheric circulation model Bedymo, which combines the quasi-geostrophic approximation and the hydrostatic primitive equations in one modelling framework. The model is designed such that the two systems of equations are solved as similarly as possible, such that differences can be unambiguously attributed to the different approximations, rather than the model formulation or the numerics. As a consequence, but in contrast to most other quasi-geostrophic models, Bedymo is using sigma-coordinates in the vertical. In addition to the atmospheric core, Bedymo also includes a slab ocean model and passive tracer module that will provide the basis for future idealised parametrisation of moisture and latent heat release. Further, Bedymo has a graphical user interface, making it particularly useful for teaching.

Bedymo is evaluated for three atmosphere-only test cases and one coupled test case including the slab ocean component. The atmosphere-only test cases comprise the growth of a cyclonic disturbance in a baroclinic environment and the excitation of Rossby waves by isolated orography, both in a mid-latitude channel, as well as the simulation of a mid-latitude storm track. The atmosphere-ocean coupled test case is based on an equatorial channel and evaluates the coupled response to an isolated equatorial temperature anomaly in the ocean mixed layer. For all test cases, results agree well with expectations from theory and results obtained with more complex models.

Clemens Spensberger et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on gmd-2021-84', Sebastien Fromang, 23 Jun 2021
  • RC1: 'Comment on gmd-2021-84', Anonymous Referee #1, 13 Jul 2021
  • RC2: 'Comment on gmd-2021-84', Anonymous Referee #2, 17 Oct 2021
  • AC1: 'Final response to the comments on gmd-2021-84', Clemens Spensberger, 17 Nov 2021

Clemens Spensberger et al.

Clemens Spensberger et al.


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Short summary
In order to understand the atmosphere, we rely on a hierarchy of models ranging from very simple to very complex. Comparing different steps in this hierarchy usually entails comparing different models. Here we combine two such steps which are commonly used in one modelling framework. This makes comparisons both much easier, and much more direct.